After considering all the advice here and in a bunch of online reviews... I have come to a decision.
I just picked up a Garmin nuvi 65LMT.
Decided that the RV specific GPS was too expensive and didn't see too many positive online reviews about them. Average price at $350 and upward to near $500... That's too much; paid $179 for the Garmin at Target.
I figure I can load my own waypoints as per Andy's and others suggestions. I usually like to plan my routes for long trips on the laptop and this allows me to do that. I'll just have to research low bridges and bad roads ahead of time on my own.
The 6 in. screen is just right, 5 in too small for my eyes and 7 in takes up too much window.
And it has free lifetime map updates and real time traffic avoidance. No cell phone required. Be advised updating maps takes about an hour
There are software upgrades (patches) that are free too. Nice to be able to get fixes as needed.
It will go for a test drive tomorrow. More later.